Video over Internet Protocol (IP) is a network-based one-way transmission of video content. The video is broadcast from a broadcasting source in a Unicast or Multicast configuration. In a Unicast configuration, the transmission is replicated by the broadcasting source for each targeted client (or viewer). In a Multicast configuration, however, the same signal is sent over the network as one transmission, but to multiple clients or a group of clients.
Currently, video over IP is used for many applications. For instance, using Motion Picture Experts Group (MPEG) compression, video over IP has been used for years in network applications such as video on demand.
Over the last few years, there has been interest in live video broadcasting over IP, which is different from other types of communications on the Internet. For example, live video broadcasting (or streaming) is one-way communication instead of two-way communication where every client receives the same data at the same time instead of at different times. Hence, under current communication systems, video over IP requires a large bandwidth to support transmissions, and for certain types of video over IP applications, such as Internet Television (IPTV) for example, demand for better video resolution, from SDTV to HDTV, requires even higher bandwidth, especially at the servers. The bandwidth requirement at the servers is generally a direct proportion of the numbers of clients.
FIG. 1 shows an exemplary graph of the bit rate and bandwidth of a server requirement for high, standard and low definition resolutions. As the number of clients or viewers increased, the larger bitrate and bandwidth is needed. In addition, better resolution means higher bitrate and higher bandwidth. If the number of client is allowed to become too large, not one but all of clients will suffer poor video and audio qualities. Bitrate and bandwidth have become one of the most critical aspects for good Quality of Service. In this solution, the Quality of Service will break down when the number of clients grown too large.
FIG. 2 illustrates one alternative solution using Peer-to-Peer network where the bitrate and bandwidth required is distributed among the clients instead of concentration at the server. Each client is required to relay the video that it received to the next client. Therefore, the number of clients can grow unlimited. However, this solution has one limitation. The bitrate of the entire network depends upon the weakest or slowest client. For this reason, the peer-to-peer network is to slow for high-resolution videos.